Calculate the atomic mass (average) of chlorine using the following data:

$\begin{array}{ccc}\text{Isotopes}& \%\text{Natural Abundance}& \text{Molar mass}\\ {}^{35}\text{Cl}& 75.77& 34.9689\\ {}^{27}\text{Cl}& 24.23& 36.9659\end{array}$

The average atomic mass of $Cl:$

Description

The average atomic weight is the total weight of the sample divided by the number of molecules in the sample.

$\therefore$ 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑎𝑡𝑜𝑚𝑖𝒄 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐ℎ𝑙𝑜𝑟𝑖𝑛𝑒$=\sum m_i\frac{A_i}{100}$

$m_i=$𝑖𝑠𝑜𝑡𝑜𝑝𝑖𝑐 𝑎𝑡𝑜𝑚𝑖𝑐 𝑚𝑎𝑠𝑠

$A_i=\%$ 𝑎𝑏𝑢𝑛𝑑𝑎𝑛𝑐𝑒 𝑜𝑓 𝑖𝑠𝑜𝑡𝑜𝑝𝑒

$\text{Average atomicmass ofchlorine}=(34.9689\times \frac{75.77}{100})+(36.9659\times \frac{24.23}{100})$

$=[26.4959+8.9568]u$

$=35.4527u$
Final Answer: The average atomic mass of $Cl$ is $35.4527u.$